A country bent on harming another nation through cyber warfare likely can’t trigger something apocalyptic, but can do serious harm. “I often tell people the threat is worse than they realize, but not as bad as they want to imagine,” Lee says. In other words, one nation probably can’t catalyze a meltdown at a nuclear power plant. But shutting off the electricity, or disrupting railroad systems, or oil and gas infrastructure, could dearly cost an adversary economically. It could even kill people, if vaccine production or a hospital were affected, for example. “It’s without a question that they could cause significant impact to human life,” Lee says.